The Philippines' military said Thursday the death toll from an assault against Al-Qaeda-linked Islamic militants had risen to 26, with one marine among the dead as troops cleared the combat area.

The latest fatalities on the southern island of Jolo bring to 33 the total number of Abu Sayyaf fighters killed in a month of operations against the group feared for its kidnapping raids.

Most of the deaths came on Tuesday amid fierce fighting after marines overran a camp on the heavily forested island the previous day. Dozens of militants and troops were also wounded.

Military spokeswoman Captain Rowena Muyuela said residents had reported additional casualties following the clashes. "This operation is part of the continuing military action against the Abu Sayyaf to rid the province of their kidnapping activities," she said.

The Abu Sayyaf camp on the fringes of the small Muslim-populated town of Patikul, 950 kilometres (590 miles) south of Manila, was seized by the military on Monday. Armed forces then used artillery and attack helicopters to target militants.

The camp had been used as a training ground for Abu Sayyaf recruits and as a launch pad for frequent kidnapping raids, said Muyuela, adding the military had found no sign of hostages at the site.

The Abu Sayyaf, formed in the 1990s with seed money from Al-Qaeda mastermind Osama bin Laden, has been blamed for the worst terror attacks in Philippine history, including kidnappings of foreigners and locals who are then held for ransom.

The group is suspected of abducting a female Chinese tourist and a Filipina resort worker from the neighbouring Malaysian island of Sabah in April. The Malaysian government said the kidnappers had demanded 36.4 million ringgit ($11.25 million) for the release of the Chinese woman.

But the whereabouts of the two women are not known. On April 11, the military launched an operation on the southern island of Basilan, another Abu Sayyaf stronghold, leaving at least seven extremists dead. A day later, another Abu Sayyaf member was killed in Jolo.

A rotating batch of about 500 US special forces have been stationed in the south for more than a decade to train the Philippines' military in how to combat the Abu Sayyaf. The group is believed to have only a few hundred militants, according to the military.

But it has been able to remain a threat and replenish its numbers with the support of local Muslim communities, some members of whom feel they have been mistreated by the country's Catholic rulers in Manila. (AFP)